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clinuxfilespawn

Maximum number of files that can be open and processes that can be spawned

When I was running a program that modifies files, and had loaded exactly 1000 files, the program aborted with the message:

Process launching failed: Too many open files

Where can I find the C constant to use in my code to figure out the maximum number of files that can be open and processes that can be spawned all at once?

Solution

  • On POSIX-compatible systems, you can use the getrlimit function with the RLIMIT_NOFILE parameter.

    #include <sys/resource.h>

rlim_t get_open_files_limit() {
    struct rlimit limit;
    getrlimit(RLIMIT_NOFILE, &limit);
    return limit.rlim_cur;
}

    Some systems (Linux, BSD, maybe others?) define an RLIMIT_NPROC on top of this which can tell you the maximum number of processes that the user is allowed to create. See FreeBSD-specific documentation, Linux-specific documentation.